Dot 4 Brake Fluid V`s Silicon Brake Fluid

[lowedb]

A few years ago I discussed this with one of our Brake development Engineers where I worked. They told me the main concern was what happened if a little water got into the system. Testing showed that this did happen and with glycol fluids it's absorbed, and then removed with the brake fluid change. With S
ilicon, the moisture still gets into the system (he didn't tell me how, so you'll have to guess) and ends up sitting in little bubbles. Generally this is in the cylinders (slave, I think he said) so you get corrosion occuring where the 'bubble' of water sits on the bottom of the cylinder.

If I get chance, I'll ask the guys where I work know why we don't use it, as I've been working with the brakes people all morning.

[RussLCV]

Silicon is great stuff, put it into the van with all new kit and 6 years later (touch wood) no problems, no seals gone and a good pedal!!

[Innovator]

I am another person that would not use Copper brake lines due to the risk of work hardening and cracking, especially when a product exists that reduces the risk substantially ie Kunifer.

I also do not use or will not use silicon because race cars do not and that tells me something. I would prefer to change my fluid every year and have a higher boiling point and firmer pedal than with silicon, but my cars brakes probably get more hammer than the average Minor.

As has been said the main reasons that car manufacturers do not use silicon is cost and contamination. A 1 Euro (yes one euro) saving on the cost of a car is considered a substantial saving.

John

[crossword]

I may be wrong but I have always believed that copper brake pipe is not permissible . Any MOT testers out there who know ?
I have & continue to make brake pipes from Kunifer tube for over 25 years.

[bigginger]

I think you're probably wrong. I don't believe anybody would still be selling the stuff if that was the case.

[rayofleamington]

Kunifer is fine by me - except when one side of the tube is harder than the other so it won't flare properly (the flares just go sideways and jam the tool).
Must now hold the guinnes book of records award for the number of pipe-related problems when I needed to replace a rear axle brake pipe (this aftenoon... evening.)


Couldn't undo the fittings - spanner turned round.
Got the neighbour out so I could borrow his brake pipe spanner (that didn't help)
cut the pipe off to use a 6 point socket on the fittings (that didn't remove the one from the T-piece - that just rounded it more)
Removed the T-piece and put it in a vice and used big mole grips to remove the stubborn fitting.
Removed the fitting but it left half the threads stuck into the T-piece.
Spent 1.5 hours removing the dead threads from the T-piece.
Realised I didn't have the right flare nuts so went to town to get some - shop now shut.
Went to another other shop, and got some flare nuts after he spent 15 minutes searching in the back of the shop.
Made up the pipe.
Cut the 2nd end off, to fit the 2nd flare nut
Re-flared the 2nd end - all done at last..... ?
Flare nut would not fit into cylinder (none of the new flare nuts would) despite being the right size and thread.
Tried filing the end to help the thread engage but that didn't help.
Cut the end off again and fitted an old (undamaged) flare nut
Had 4 attempts (cutting the end off each time) as the pipe would not flare properly due to having a hard spot. Tried a different piece of tube and it flared fine
Fitted pipe to T-piece and then onto car 5 hours after starting.
Unfitted it from T-piece so that I could screw the T-piece back onto the flexi.
Refitted it - bled brakes.
1/2 hour job done in 6 hours....

[crossword]

Ray, that sounds just like the joys of motoring in cars almost as old as me !
Andy